Multilayer substrate

1. A multilayer substrate, comprising

a signal layer that includes a first line and a second line which form a differential pair,

the first line electrically connecting a first node and a second node in the signal layer,

the second line electrically connecting a third node and a fourth node in the signal layer,

an interval between the first line and the second line being approximately constant from the first node to the second node,

a physical length from the third node to the fourth node in the second line being shorter than a physical length from the first node to the second node in the first line, and

a width of the second line being thicker than a width of the first line.

2. The multilayer substrate according to claim 1 ,

wherein the width of the first line is approximately constant from the first node to the second node, and

the width of the second line is approximately constant from the third node to the fourth node.

3. The multilayer substrate according to claim 1 ,

wherein an average value of a radius of curvature of a second curve along the second line is smaller than an average value of a radius of curvature of a first curve along the first line.

4. The multilayer substrate according to claim 3 ,

wherein the first curve and the second curve are bent to one direction side in a width direction, and

the second curve is located on the one direction side in comparison to the first curve.

5. The multilayer substrate according to claim 1 ,

wherein, if the width of the first line is set as W 1 , the width of the second line is set as W 2 , the physical length of the first line is set as L 1 , and the physical length of the second line is set as L 2 , then a relationship of

W 1< W 2<{( L 1)/( L 2)}× W 1

is established.

6. The multilayer substrate according to claim 1 , further comprising

a ground layer,

wherein the signal layer is disposed above the ground layer.

7. The multilayer substrate according to claim 6 ,

wherein the ground layer has a planar pattern that extends in a planar shape.

8. The multilayer substrate according to claim 1 , further comprising

a common mode filter that is disposed to the first line and the second line.

9. The multilayer substrate according to claim 8 ,

wherein the common mode filter includes:

a first inductance element that is electrically inserted into the first line;

a second inductance element that is electrically inserted into the second line; and

a core that magnetically couples the first inductance element and the second inductance element.

10. The multilayer substrate according to claim 1 ,

wherein the first line and the second line transmit a radio-frequency differential signal.

11. The multilayer substrate according to claim 1 , further comprising

a second signal layer that includes a third line and a fourth line which form a differential pair,

wherein the third line electrically connects a fifth node and a sixth node in the second signal layer,

the fourth line electrically connects a seventh node and an eighth node in the second signal layer,

an interval between the third line and the fourth line is approximately constant from the fifth node to the sixth node,

a physical length from the seventh node to the eighth node in the fourth line is shorter than a physical length from the fifth node to the sixth node in the third line, and

a width of the fourth line is thicker than a width of the third line.

12. The multilayer substrate according to claim 11 ,

wherein the width of the third line is approximately constant from the fifth node to the sixth node, and

the width of the fourth line is approximately constant from the seventh node to the eighth node.

13. The multilayer substrate according to claim 11 ,

wherein an average value of a radius of curvature of a fourth curve along the fourth line is smaller than an average value of a radius of curvature of a third curve along the third line.

14. The multilayer substrate according to claim 13 ,

wherein the third curve and the fourth curve are bent to one direction side in a width direction, and

the fourth curve is located on the one direction side in comparison to the third curve.

15. The multilayer substrate according to claim 11 ,

wherein, if the width of the third line is set as W 3 , the width of the fourth line is set as W 4 , the physical length of the third line is set as L 3 , and the physical length of the fourth line is set as L 4 , then a relationship of

W 3< W 4<{( L 3)/( L 4)}× W 3

is established.

16. The multilayer substrate according to claim 11 , further comprising

a ground layer,

wherein the signal layer is disposed above the ground layer, and

the second signal layer is disposed below the ground layer.

17. The multilayer substrate according to claim 16 , further comprising:

a first via that connects one of the first node and the third node to the fifth node; and

a second via that connects the other of the first node and the third node to the seventh node,

wherein the ground layer has a planar pattern that extends in a planar shape, and has an opening that surrounds the first via and the second via.

18. The multilayer substrate according to claim 11 , further comprising

a second common mode filter that is disposed to the third line and the fourth line.

19. The multilayer substrate according to claim 18 ,

wherein the second common mode filter includes:

a third inductance element that is electrically inserted into the third line;

a fourth inductance element that is electrically inserted into the fourth line; and

a second core that magnetically couples the third inductance element and the fourth inductance element.

20. The multilayer substrate according to claim 11 ,

wherein the first line and the second line transmit a radio-frequency differential signal, and

the third line and the fourth line transmit a radio-frequency differential signal.